Conventionally, problems of poor signal reception, a too-slow transmission rate and the like are often encountered when a wireless mobile communication network is used indoors. Although a variety of communication devices using different network interfaces (e.g., Wireless Fidelity (Wi-Fi)) and High Speed Packet Access (HSPA)) have been provided in the market to solve these problems, these communication devices increase the cost for the users.
The Femto Forum established in 2007 has proposed a Femto Access Point (FAP) to solve various problems of indoor wireless mobile communication networks completely. An FAP is an access point (AP) of a low power level that uses a licensed wireless frequency band at a front end thereof, so no changes need to be made on the user's equipment. For the operators, a larger wireless network coverage rate may be achieved in an indoor environment by use of an FAP. A back end of the FAP is connected to an operator's network through an existing wired network technology (e.g., through a Digital Subscriber Line (DSL) modem or through a cable modem) to facilitate the operator to provide better network management services.
FIG. 1 depicts a conventional network system 1 that adopts an FAP architecture. The network system 1 comprises an FAP 115, a modem 117, a security gateway 121 and a femto gateway 123. The modem 117 may be any modem connectable to a home broadband network 119, for example, a DSL modem or a cable modem. The FAP 115 is connected to the security gateway 121 via the modem 117 and the home broadband network 119. The security gateway 121 is in turn connected to the femto gateway 123 and further to the Internet 125. The home broadband network 119 and the FAP 115 may belong to different operators; in other words, data transmitted by the FAP 115 may be transmitted through other operators' network. In view of this, a secure channel must be established between the FAP 115 and the security gateway 121 to secure data transmission therebetween. The femto gateway 123 is responsible for establishing data flows of a first mobile station 111 and a second mobile station 113 and acts as a gateway between the internal network and an external network.
Both the first mobile station 111 and the second mobile station 113 are connected to the Internet 125 via the femto gateway 123. If the first mobile station 111 intends to transmit data to the second mobile station 113, the data must be transmitted to the femto gateway 123 via the FAP 115, the modem 117, the home broadband network 119 and the security gateway 121 at first and then transmitted to the second mobile station 113 via the security gateway 121, the home broadband network 119, the modem 117 and the FAP 115 from the femto gateway 123.
The transmission method described above has the following three disadvantages: firstly, the data transmission rate is restricted by the home broadband network 119. As currently the home broadband network 119 generally has a bandwidth of around 10 Mbps which is still lower than that can be provided by a wide area network system (e.g., a Worldwide Interoperability for Microwave Access (WiMAX) network system), the bandwidth that may be enjoyed by the user is restricted by the home broadband network 119; secondly, data transmission is accomplished through networks and network equipment provided by a lot of Internet service providers (ISPs), so a considerable latency and signal jitter may be caused; and thirdly, as private data of the user must be exposed to the networks of the ISPs, there is a significantly higher possibility of data breach.
Accordingly, for network systems adopting the FAP architecture, there remains a need in the art to provide a solution that can enlarge the bandwidth available for use by mobile stations and enhance the security of data transmission when the mobile stations served by the network systems intend to transmit data within a local area network (LAN).